<html>
    <head>
        <title>el:挂载点</title>
    </head>
    <body id="body">
        {{message}}
        <h2 id="app" class="app">
            {{message}}
            <span>{{message}}</span>
        </h2>
        <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
<script>
    var app=new Vue({
        //el:"#app",
        //el:".app",
        //el:"div",
        el:"#body",
        data:{
            message:"黑马程序员"
        }
    })
    </script>
    </body>
</html>